This invention is directed generally to the field of disc drives, and more specifically for an improved electrical connector for a motor which is especially useful in disc drives.
Winchester disc drives are being used in computers to store increasingly large amounts of information; their long term reliability as well as cost of production in an age of reduced prices for personal computers is critical. The typical Winchester disc drive is a system with a limited number of mechanical parts, including a spindle motor which mounts one or more discs for constant speed rotation, and an actuator carrying a transducer at one end and a voice coil motor at the other and operable in response to commands to the voice coil motor to position the transducer over a selected track to read and write data.
As one of the most expensive elements of a disc drive, as well as one of the largest and most mechanically complex, many design efforts are intended to minimize the cost and ease of assembly of the spindle motor. This particular invention is especially directed to improving a spindle motor design which incorporates a central connector which extends through the bottom of the shaft and into and through the base of the disc drive, so that external connections can easily be made from below the motor to a control board attached to the housing which will supply energizing current to the disc drive spindle motor. It is apparent that it is essential to provide a reliable connector from the source of external power to the stator of the spindle motor so that the motor can be reliably energized. Over time, the disc drive and the motor which runs at constant speed for hours at a time can be subjected to shock and continuing vibration; this could easily cause connections to loosen or a plug which inserts the connections into the base of the motor to even become lose and slip out of the motor, causing the disc drive to lose power. Any slippage or deterioration in the quality of the plug connector could cause such a loss of power. Therefore, an improved connector which can fit into the hollow center of a shaft and which will provide a long lifetime without deterioration of the electrical contacts is highly desirable.
Therefore, it is an object of the present invention to provide an improved spindle motor design for use in a disc drive.
A related invention is to provide a simplified spindle motor design with a reliable connector inserted into a hollow shaft of the motor.
A further objective of the invention is to provide a connector which incorporates spring contacts which establish a pressure contact between the conductive lines on the flexible printed circuit and the conductors led into the plug connector.
Another related objective of the invention is to provide a motor connector which can be easily plugged into the hollow shaft of a motor at any time during the assembly of the motor so that assembly and testing of the motor can be an optimized sequence.
A further objective of the invention is to provide a strain relief on the flexible printed circuit which is incorporated in the connector so that it cannot be disengaged from the connector.
Yet a further objective of the invention is to provide for assembly of the plug connector without the use of solder or the like, which can lead to breakage or lost contact, but rather by a press fit connection.
These and other objectives of the invention are achieved by providing a connector assembly comprising a base portion which plugs into the base of the motor shaft and a connector body having electrical interface rods along an axial face thereof. A flexible printed circuit having one end connected to the stator has dedicated connector pads on a surface thereof which line up with and are intended to be pressed against the molded body connector rods. To maintain the pads and rods in tight electrical contact, a connector snap spring assembly is snapped in place over the connector body. The snap spring assembly, for ease of manufacture, is assembled in two parts comprising a first U-shaped connector snap having a base and two arms, the arms being sized and adapted to snap over shoulders of the molded body; and a connector spring which is pressed in place over the body of the connector snap and includes a plurality of flexible fingers which are aligned with the flexible printed circuit pads and the molded body connector rods so that when the arms of the snap spring assembly are snapped over the shoulders of the body, the springlike fingers tightly press the pads and connector rods together. In order to prevent the flexible printed circuit from being pulled out from between the snap spring assembly and the body, a hole is formed in the printed circuit axially displaced from the connector pads; a finger extending radially from the connector body passes through this hole to maintain the axial alignment of the flexible printed circuit with the remainder of the press fit connector. The connection of the molded body and connector snap spring assembly is further enhanced and maintained by making their total outer dimension about the same as the width of the opening in the hollow shaft so that when the assembled connector plug is inserted in the hollow shaft, the inner walls of the shaft press the two parts of the connector together.
Other features and advantages of the present invention will be better understood by reference to the following figures and the detailed description of an exemplary embodiment or embodiments given in conjunction with these figures.